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FUSE

Original Filed Sent. 16. 1929 www w m N M m Reissued Nov.- 1.0, 1,936

UNITED STATES FUSE Alwin G. Steinmayer, Milwaukee, Wis., assignor to Line Material Company, `South Milwaukee, Wis., a corporation of Delaware Original No. 1,932,194,

dated October 24, 1933,

Serial No. 393,038, September 16, 1929. Appliv cationI for reissue March 4, 1935, Serial No.

5 Claims.

This invention relates to certain new and useful improvements in fuses and refers more particularly to a'. fuse for use with high tension circuits and particularly adapted for low am- 5 per-ages. A

Heretofore, fuses of this type have been formed of a single piece of fusible metal, maintained under'tension by a spring, so that uponI rupture of the fuse, the released energy of the spring would quickly draw one of the fuse element terminals out of its voperative position to increase the gap between the terminals. `This construction, however, was objectionable when usedwith lower amperages as the fusible' element, in such instances, is necessarily light and consequently so mechanically weak that it could not stand the strain ofthe continuous tension applied by the spring. It is, therefore, one of the objects of this invention to provide a. fuse of the character described which will rupture at the desired low amperage and which has sufdcient mechanical strength to withstand a continuous tension thereon.

Another 'object of this invention. residesin providing a fuse of the character described which may be re-fused in the field. n

Another object of this invention resides in the provision lof an improved method of venting accumulated gases upon rupture of the fuse.

And a more specific object of this invention resides in the provision oi' a fuse of the character described having a pair of fuse elements soldered together for a portion of their length whereby suilicient mechanical strength is obtained to 35 withstand the tension to which the fuse is subjected Vwithout increasing itsvcurrent carrying capacity.

With the above and other objects in view which vention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly deiined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

In the accompanying drawing, I have illus will appear as the description proceeds, my in-A (Cl. 20o-117) Referring now more particularly to the accompanying drawing the numeral 5 represents the tube or cartridge of the fuse which is preferably formedyof glass or similar material and to the ends of which contacts 6 and 'l are secured in any suitable manner. The contact 1 is provided with an axial threaded recess Il communicating with'the interior of the tube to receive a longitudinjaliy bored nut member 9. One end of a flexible-conductor cable I I, is passed through the bore III of the nut member to be folded upon itself as at I2 and impinged between the bottom of the recess and the lower face of the nut member to provide a good electrical connection between the ycontact and the flexible. conductor.

The exible conductor II electrically connects the contact 1 with one end of a fuse element indicated generally as at I1 by having its free end soldered or otherwise secured in an aperture I3 formed in a fuse terminal 'Il having a transverse opening I5 and a bored recess I6 projecting downwardly from its upper end toreceive the said end of the fuse element. The fuse element I1 consists of two similar sections I8 and I9 formed of comparatively heavy wire of the same ordiii'erent materials, depending upon the amperage at which the fuse is to be ruptured, and having their adjacent ends soldered together as at 20. The solder used may be either a pure tin or a special alloy, the pure tin however being preferable as it has greater mechanical strength.

'Ihe wires of which the sections I8 and I9 -are formed, may be-ofany suitable metal as for in- A stance, nickel-silver, which has ,exceptionally high mechanical strength and sufllcient resistterminal member Il, is secured therein by a set which is received in the bored recess I6 of the .screw 2l and the free end of the section I8 is` 'through the fuse element and the iiexible conductor I I.

To maintain the cap25 seated in its `bore 25 and to insure the immediate provision of a large gap between the contacts upon melting the solits other end being received in a transverse opening 29 in the nut member.

To confine the arc incidental to'therupture of the fuse to its immediate vicinity the sections l I9 and I9 comprising the fuse element are surrounded bya cork sleeve 29 having a longitudinal opening slightly larger than the size of the fuse element, and to further insure quick extinguishment of the arc, the entire tube is preferably filled with a suitable fluid havinga high degree of dielectric strength. In the event of an overload in the circuit including the fuse, the increased current heats the fuse element and melts the solder connecting its sections- I9 and I9, permitting the spring 21 to quickly separate the sections and produce a relatively large gap between the contacts. In the event of an extremely largeoverload, the resulting explosion merely blows the cap 29 from its seat tov vent the gases and thus precludes the possibility of demolishing the entire fuse.

From the foregoing disclosure it is obvious that the section I9 of the fuse element comprises a relatively rigid portion extending from the terminal Il into the bore of the sleeve 29, whereby when the sections I9 and I9 are separated under Voverload conditions, an arc will be drawn in the bore of the sleeve 29.

I'he'bore of the sleeve 29 is preferably uniform in diameter throughout the length of the sleeve and is relatively smaller than the bore of the cartridge i, butit is preferably larger than the section I9 in order to permit gases generated by the heat of the arc to expand freely.

It may be clearly seen from the drawing that, since the lower end of the bore in the sleeve 29 is closed by the terminal Il, liquid will be prevented from entering the lower end of the bore. As a result, liquid in the bore will not be replaced by cooler liquid which would tend to cool the fuse element Il and delay the separation of the sections I9 and I9.

.Obviouslysthe sleeve 29 composedof insulating material other than cork, the material comprising the sleeve being entirely within ity with the results desired. Preferably thev the choice of the manufacturer and in conformsleeve -29 should rest on the terminal Il to substantially close the lower end of thebore in the sleeve. However, even though the sleeve 29 may be forced upwardly by the liquid and into contact i with the boss 24, the formation of vapor in the bore of the sleeve may create sumcient pressure upon the liquidl in the bore to force the liquid out at the lower end thereof and prevent cooler liquid from entering therein, thus insuring a reasonable degree o f accuracy in the pointof overload at which `the fusible element Il will separate. l

Irrespective of whether the sleeve 29 rests on the terminal I4 or against the boss 2l, the eifect will be to prevent liquid exteriorlyof the sleeve 29 from entering the bore thereof and. replacing warmer liquid in the bore when the fusible element I1 issubjected to an overload.

It is also noted-that re-fusing in the eld is not only possible but practical. Those skilled in the art to which this invention belgngswill understand that the flexible conductor .II should be suillciently long, to permit the fuse terminal Il a therewith to be'drawn out through the-opening 29 in the contact 9, with the aid of a hooked wire' tional liquid also may be added.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent to those skilled in the art to which this invention appertains, that I provide a novel fuse structure which is particularly adapted for use with low amperages, in which the existing objection to fuses maintained under tension by a spring is eliminated, and in which re-fusing'in the ileld is made practical. f What I claim as my invention is:`

1. In an expulsion `fuse of the character described, the combination of a tube of insulating material, a metal cap mounted on each end of the tube, the side walls of which are 'adapted for engagement with terminal clips, the end wallof one cap being imperforate to completelyclose said end of the tube, while the end wall o f the other cap has a tapered bore forming a ventopening, the closed end wall of the ilrst mentioned cap having 'an internally threaded recess, a plug detachably secured in said recess, said plug having an opening therethrough leading to the bottom of the recess, a exible conductor having one end passed through said opening to be folded over and clamped between the bottom of the recess and the adjacent end of the plug', a terminal member fixed the oppositel end of the flexible conductor, a. second terminal member having an enlarged frustro-conical head seated in said tapered bore in the other cap, a fuse element readily detachably connected at its opposite ends with said terminals to electrically bridge the same, whereby said caps at the ends of the `tullesare electrically connected through the fuse element and the flexible conductor, and a tensile spring having one end connected with the plug-at the rst mentioned cap and its vother end engaging in major part in said liquid; said means including a fusible section, a exiblesection, a relatively rigid section connecting` the fusible section and the ilexible section, a spring coaxial with the flexible section, and means connecting the 'spring with said relatively rigid section; of an arcing sleeve comprising insulating material surrounding and axial with the relatively rigid section,` the bor of the sleeve being' larger in diameter than the relatively rigid section and being substantially uniformin diameter and unobstructed throughout the length of said sleeve. thereby to provide an arcing space surrounding the relatively rigid section for the free expansion of gases produced by an arc when the fusi- 4ble section is fused, and means on one of said imity to the means connecting the spring with said relatively rigid section, the ilrst-mentioned means being normally disposed adjacent the lower end of said bore.

3. In a fuse, a main tube having -upper and lower terminal contacts, a conductor in said tube connecting said terminal contacts, said conductor comprising a fuse element including a relatively the exible portion, in combination with an arcrigid portion, a ilexible portion and a movable terminal portion connecting the relatively rigid portion and the flexible portion, in combination with an arcing tube in the main tube surrounding the relatively rigid portion, the bore of said varcing tube being larger in diameter than the cross-sectional width .oi the relatively rigid portion lin said arcing tube, whereby gases may freely expand in said arcing tube without injury thereto, a spring connected to the'terminal portion for withdrawing said relatively rigid portion from said arcing tube when said-fuse element is ruptured, an anchorage for the other end of said spring disposed on the lower end of the main tube, and means carried by the upper contact adapted to confine said arcing tube in close proximity to the terminal portion, said terminal portion being normally adjacent the lower end of the bore in said arcing tube. n

4. In a iuse, a main tube having terminal contacts, a conductor in said tube connecting said `terminal contacts, said conductor comprising a fuse element including a relatively rigid portion, a flexible portion and a movable terminal portion connecting the relatively rigid portion and ing tube in the main mbe and having a bore slightly larger than the transversedimension of the relatively rigid portion, said arcing tube surrounding the relatively rigid' portion, spring means connected with said terminal portion for withdrawing' said relatively rigid portion from said arcing tube when said fuse element is ruptured, and means on one of said contacts adapted to conne said arcing tube in close proximity to said terminal portion.

5. In a ruse, a conductor comprising a fuse elementy including a relatively rigid portionwa relatively exible portion, an arcing tube having a relatively small bore oi unvarying dimension from end to end and slightly larger than said relatively rigid portion, the bore in said tube being unobstructed and surrounding'the relatively rigid portion, a terminal connected to said relatively rigid portion, and a spring tensioning said fuse element and connected to said terminal. said terminal being disposed adjacent the lower end of said bore, whereby to cause the relatively rigid portion to be projected from the end of the tube when said fusible element is ruptured.

ALWIN G. erhmmm. 

